(a) Technical Field
The present invention relates to the treatment of offensive odors and toxic substances of foundry waste. More particularly, it relates to an advanced oxidation system for the treatment of offensive odors and toxic substances of waste foundry sand and a treatment method using the same, which can effectively remove offensive odors and toxic substances produced during a sand reclamation process for reclamation of waste foundry sand.
(b) Background Art
The improvement of the environmental standards in recent decades has increased people's interest in the industrial community's effect on the environment. As cities expand, large-scale residential areas have become established around industrial complexes previously located on the periphery of the cities. As a result, there has been an increase in the number of civil complaints from residents of the surrounding communities, especially regarding offensive odors and the like.
Accordingly, local government has imposed strict regulations on offensive odors and toxic substances, which typically require a counter-plan for reducing the emission of offensive odors and toxic substances which impact on the environment surrounding these factories. In particular, foundries have been affected by these laws and regulations because they typically emit toxic substances such as phenols, amines, etc., whose odor can be detected even at a very low concentrations and is therefore subject to the regulations. For example, phenols and amines are generated mainly by pyrolysis of phenol resin as a bonding agent and amine as a curing agent or hexamine as a curing accelerator used for sand bonding by pouring.
In the foundry, the offensive odors are emitted during the core manufacturing process, a pouring/cooling process, a de-molding process, and a sand reclamation process. Among these four processes, a wet suppression system is provided at the end of each of the core manufacturing process and the pouring/cooling process to minimize the emission of offensive odors and toxic substances. In the de-molding process, a wet suppression system for removing dust is converted into a dry suppression system to treat the dust, offensive orders, and toxic substances. However, in the sand reclamation process, the transfer distance using a conveyer is too long to install appropriate local exhaust system and air suppression system.
The sand reclamation process typically includes a crushing process which crushes the waste foundry sand into sand granules, a transfer process that transfers the sand granules using a conveyor, a sieving process that removes the remaining waste foundry sand, and a mixing process that mixes the waste foundry sand granules, new sand, clay, sea coal, and water. In all the unit processes, offensive odors and toxic substances are emitted from the waste foundry sand and thus, dispersed and scattered over a workplace and the neighboring residential area (i.e., the civil complaint area).
As shown in FIG. 1, in the conventional sand reclamation process, the crushing process, the sieving process, and the mixing process are not provided with a separate system for the treatment of offensive odors and toxic substances other than a dust treatment system (i.e., dry suppression system), and thus only the dust is removed. However, the offensive odors and toxic substances are still emitted to the air. More specifically, the transfer process, which uses the conveyor, is not provided with a local exhaust system and an air suppression system, and thus the dust, offensive orders, and toxic substances are scattered over the workplace and dispersed into the outside of the foundry during the transfer process.
In order to reduce the emission of offensive odors and toxic substances during the sand reclamation process, it would be beneficial to install and manage a wet suppression system in each process. However, when the wet suppression system is installed in each of the four processes, the initial investment costs are very high, and further the annual operating expenses are significantly increased. As such, to install and manage the wet suppression system in the sand reclamation system, the investment costs would be extensive, and when there is not sufficient space the foundry, it is very difficult to install the wet suppression system.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.